The present invention relates to a starter dynamo. More particularly, it relates to an improvement in a starter dynamo used, for instance, for automobiles.
A dynamo is connected to an output shaft of an engine to perform starting of the engine and generation of electricity. A dynamo generally used is constructed as shown in FIGS. 1 and 2. In the Figures, a reference numeral 1 designates a flywheel magnet comprising a flywheel 4 firmly connected to an end of a crank shaft 3 which is provided in an engine 2. A numeral 5 designates an armature screw-fitted to a part of the engine 2, the armature being constitued by an armature core 6 and a coil 7 for lighting and charging, wound around the armature core 6. The flywheel 4 includes pieces of magnetic steel 8 and pole cores 9 which are fixed into one body in an aluminum die-cast body 10. A numeral 11 designates a bearing mounted on a part of the engine 2 to support the crank shaft 3 in a freely rotatable manner. A numeral 12 designates a diode which rectifies an a.c. power output produced in the coil 7 to supply it to a battery 13, a numeral 14a designates a switch connecting a terminal of the coil 6 to the anode of the diode 12 by switching an intermediate tap and a numeral 14b designates a switch which is operated in association with the switch 14a and supplies the a.c. power output produced in the coil 7 to lamp 15 mounted on an automobile.
In the dynamo constructed as above-mentioned, actuation of the engine rotates the crank shaft 3 and the flywheel 4 connected to the crank shaft 3 is rotated. When the flywheel 4 is rotated, a rotating magnetic field produced by the pieces of magnetic steel 8 provided in the flywheel 4 acts on the armature 5 thereby generating an electormotive force of an alternating current in the coil 7. The electromotive force of the alternating current is applied through the switch 14a to the diode 12 where it is subjected to rectification and the rectified current is charged in the battery 13. Otherwise, the electromotive force of alternating current is applied to the lamp 15 througth the switch 14b operated in association with the switch 14a to operate the lamp.
The conventional device has, however, a disadvantage of a complicated structure of the device because it is necessary to install a starting device for the engine separately. To solve such problem, there has been proposed a starter dynamo in which a charging generator and a d.c. motor having function of a starter motor are connected to a crank shaft. The proposed starter dynamo had still another disadvantage that the life time is extremely short because as the revolution of the engine increases, the starter dynamo is also rotated at a high speed.